New services continuously are being added to existing wireless communications systems. Some of the most popular services are related to providing and receiving multimedia via mobile equipment, such as mobile telephones, personal digital assistants (PDAs) (or similar/related hand held devices such as PBX wireless devices), SIP phones, and lap top computers. Many of these services are provided via the Internet protocol multimedia subsystem (IMS) conceptualized by the 3GPP standards body. Typically, when a new service is introduced into a wireless network system, few customers are subscribers to the new service. Thus, service providers tend to allow users to pay for services as used. Such pay-per-use functionality allows users to get acquainted with a service before deciding to subscribe.
Users prefer to know how much a service will cost before using the service. Accordingly, some service providers provide the cost of a service to a non-subscribed user when the user requests the service before actually providing the service. The user then has the opportunity to accept or decline the service. Providing the cost for a one time use of a service before the service is provided often is referred to as “Advice of Charge,” or AoC.
Wireless and wireline communications systems too, continuously are being updated. Although the industry specifications for IMS are being developed within the industry standards, the realization of IMS has not truly matured. Thus, all desired features and/or specialized system functions have not been clearly defined/developed. This creates a challenge for carriers attempting to deploy IMS systems in which not all new systems and not all system upgrades are compatible with all new services. For example, not all IMSs are configured with the same components, and not all IMS services utilize the same components. Some IMS-based services comprise a component known as an application server (AS) as specified in the 3GPP standards. In services comprising an AS, the AS may support access to services by non-subscribed users. In this case, it would be natural for the AS to provide AoC functionality to a user. However, not all IMS-based services comprise an AS.